Kindly guide me.
What do you mean by "USDT" accepted widely? you mean accepted as in accepted to buy other cryptos? because I dont know a single business accepting USDT for payments.
Im not sure but I think the only exchange with relevant USDT volume is Poloniex:
https://poloniex.com/exchange#btc_etc
Im not sure about any way to buy USDT directly with USD, so simply buy BTC then USDT if you want USDT.
The reason USDT is only available on Poloniex is that it is a currency made by them. It was made to make traders' lives easier, they can save their profits in a currency that always has the exact same value as the dollar, minimising risk of losing money through a cryptocurrency decreasing in price. It is fairly well-established and trustworthy, but I wouldn't advise storing Tether for long periods of time, since if Poloniex experiences problems in the future, Tether may be at risk.
So USDT doesn't have its transactions on a blockchain of his own? It can't be considered a cryptocurrency right or can it?